Abstract: This paper introduces the application research of non-coal-pillar mining technology under the condition of extremely thick and hard conglomerate roof in Donglin Coal Mine.The engineering geological division of the test working face is carried out, and the constant resistance and large deformation anchor cable, blasting pre-cracking, and roadway and gangue retaining support schemes are designed.After on-site industrial experiments and mine pressure monitoring, the coal non pillar mining technology is successfully applied mine in extremely thick and hard conglomerate roof conditions.This study supplements the non-coal-pillar mining technology system, and the proposed technology and method have strong applicability, and also have certain guiding significance for the safe and efficient mining of related coal mines.